The likely operator of a new trash-burning system for the Capitol has a history of tussles with state environmental regulators.

Covanta Energy’s past problems will likely come under more scrutiny from Congressional Democrats, who have already raised concerns about the proposed scheme to turn the Hill’s trash into electricity.

Under a new contract signed by the Architect of the Capitol, the Capitol will now dispose of 90 percent of its nonrecyclable solid waste through “waste-to-energy” — the process of burning trash to create energy.

The contract employs a local vendor, Washington, D.C.-based Urban Service Systems Corp., to transport Congress’ trash to a waste-to-energy facility, which will likely be run by Covanta Energy, given its nearby locations in Virginia.

Owning or operating 40 facilities throughout the U.S., Covanta has been lauded as a pioneer in the field. And supporters say waste-to-energy, in general, is a cheaper alternative to creating energy than burning coal and a more responsible route to take than allowing trash to remain in landfills, where it releases harmful methane emissions over time.

“The waste will ... [generate] enough electricity to power an office building the size of the Dirksen or Longworth Building for several months,” Architect of the Capitol Stephen Ayers said in a statement last Thursday. He noted that Congress produced more than 5,300 tons of waste in fiscal 2010.

House Administration Chairman Dan Lungren (R-Calif.), whose panel proposed this concept to the AOC’s staff, praised the program as a “win-win” that will save Congress about $60,000 annually.

But over the past decade, Covanta has been subject to several violations in a number of states, relating to reporting, equipment malfunctions and levels of emissions of possible carcinogens.

Earlier this year, Covanta settled with the Connecticut Office of the Attorney General to pay $400,000 for exceeding allowable dioxin levels at its plant in Wallingford. The lawsuit was filed last year by the state’s then-attorney general, current Democratic Sen. Richard Blumenthal.

In 2008, the Pennsylvania Department of Environmental Protection fined the Covanta facility in Chester with $45,600 in civil penalties for emission levels of nickel, a waste byproduct, that were more than double what was permitted under its permit.

And at the Covanta facility in Alexandria, Va., a 2002 citation and fine of $14,695 from the Department of Environmental Quality was handed down for a failure to produce quarterly emission reports.

There have been other violations and subsequent penalties for various infractions at Covanta locations in New Jersey and Massachusetts.

Covanta defended its overall record.

“Should these violations have happened? No,” Covanta Chief Sustainability Officer Paul Gilman said. “But they are few and far between, and we are looking to make them extinct.”

Gilman suggested it has not always been easy to be in compliance 100 percent of the time when environmental standards differ from state to state. New Jersey and Pennsylvania do not give waste-to-energy plants any warning to address malfunctioning equipment, for instance, before issuing a notice or fine.

In the Virginia incident, the facility’s environmental specialist responsible for filing emission reports was unaware that he was required to do so quarterly rather than semiannually. That individual is no longer with Covanta, Gilman said.

Gilman also emphasized that Covanta has always been quick to address the issues at hand and has not shied away from taking responsibility, when appropriate. He added that none of these instances put public health at risk.

Ted Michaels, president of the Energy Recovery Council — a trade association for waste-to-energy operators — said Covanta’s history of violations was not unusual.

“To some extent, it’s the nature of the business: These are machines, after all, and they are not perfect, and they sometimes operate in a way you didn’t intend them to,” Michaels said. “I would think these violations would be applicable to any facility operating under a complicated Clean Air Act permit.”

One of Covanta’s main competitors, Wheelabrator Technologies Inc., has also been the subject to environmental scrutiny: In May, it was fined $7.5 million by the state of Massachusetts, “the highest ever for a state case arising out of environmental violations,” according to Massachusetts Department of Environmental Protection Commissioner Kenneth Kimmell.

For some environmentalists, that indicates the bigger problems with waste-to-energy technology in general.

“Our research shows that per hour of energy they generate, waste-to-energy incinerators are dirtier than coal-fired power plants for a range of pollutants,” said Robbie Orvis, a research analyst with the Environmental Integrity Project, noting that Rhode Island and Massachusetts have banned construction of any new facilities.

On Capitol Hill, lawmakers have showed mixed reactions to news that Congress would burn its trash.

Last week, Rep. Zoe Lofgren, a member of the House Administration Committee, was adamant in her opposition.

“I don’t agree with it,” the California Democrat said. “Why the Republicans are choosing pollution at every step is beyond me.”

The proposal comes amid a broader fight in the House over environmental practices.

Early in the 112th Congress, Republicans scaled back programs associated with House Minority Leader Nancy Pelosi’s (D-Calif.) Green the Capitol Initiative, ending a composting program and replacing biodegradable dishware in House dining facilities with those made from Styrofoam.

But a number of other House Democrats who work on environmental issues said they were willing to give the program the benefit of the doubt. Still, they said their support will depend on the environmental history of the plants ultimately selected,

“I’m totally open to it, if it’s done right,” Rep. Peter Welch (D-Vt.) said last week.

On Wednesday, Welch spokesman Scott Corriell said that in light of revelations about Covanta’s record, the Congressman “would hope that the AOC looks into any concerns about this vendor.”

Eben Burnham-Snyder also said that his boss, Natural Resources ranking member Ed Markey (D-Mass.), was generally supportive of waste-to-energy.

He added, though, that this program should not be in the place of the sustainability initiatives that preceded it.

“Regardless of the quality of the waste-to-energy technology employed, it won’t compare to the better system implemented by Nancy Pelosi in the previous two sessions of Congress,” Burnham-Snyder said.